1. Field of the Invention
The present invention relates generally to disc drives and more specifically to a mechanism for raising and lowering a disc cartridge holder between a position in which a disc cartridge can be inserted into the holder and a fully loaded position wherein the disc cartridge is placed in an operative position on a turntable and which features the use of inclined guide means for achieving the above mentioned holder movement.
2. Description of the Prior Art
FIGS. 10 and 11 show a prior art mechanism used to raise and lower a disc drive cartridge holder 104 between insertion and fully loaded positions P1 and P2. In this mechanism guide members 106, 106 are arranged on the side edges 105 of the holder proximate the forward and rear ends thereof. A slide plate 107 has vertically extending side walls 108 in which guide slots 109, 109 are formed. The slide plate 107 is arranged to be movable in the fore and aft directions between positions P3 and P4. During the movement from position P3 to P4 the guide members 106 enter the guide slots 109 and the cartridge holder is drawn down from the insertion level P1 to an operative level P2. Conversely, when the slide plate 107 undergoes a P4 to P3 change in position, the cartridge holder is moved upwardly from position P2 to P1.
It should be noted that an eject button 111 is operatively connected with the chassis of the slide plate 107 in order to enable the manual movement of the cartridge holder 104 from the fully loaded position to the insertion or loading one.
Normally, in order to permit the disc to be placed in a drive condition relative to the turntable, the disc 112 is provided, as shown in FIG. 13, with a plamag (ferrite filled plastic material) or the like type of disc hub 113 which can seat on a chuck yoke 114 of approximately the same size. In this instance the chuck yoke 114 is rotatably supported on a shaft 115 and provided with an offset drive pin 116. The disc hub 112 is formed with apertures 117 and 118 which respectively receive the upper end of the shaft 115 and the drive pin 116.
This arrangement enables the disc to be driven synchronously with the chuck yoke 114.
The turntable drive arrangement is such that the shaft 115 is placed in direct drive connection with a spindle motor and the former is operatively connected with the chuck yoke 114 by way of a belt or the like.
However, with this prior art, the mechanism for raising and lowering the cartridge holder is usually arranged such that the guide members take the form of guide rollers. However, this type of construction induces the following drawbacks.
(1) Because guide rollers are used, the number of moving parts is increased and the amount of machining and the like, which is inherently required to rotatably mount the rollers, increases the cost of the device.
(2) As shown in FIG. 12, when the holder is in the cartridge insertion or loading position the axis of each roller is located in the position denoted by O.sub.1, while when in the loaded or operative position, the axis is located in the O.sub.2 position. Thus, if the stroke of the slide plate 107 is X and the amount of vertical displacement of the cartridge holder is Y, then the O.sub.1 O.sub.2 angle is given by .theta.1=tan.sup.-1 Y/X and, in order to use the rollers, the guide slots 106 must be formed at an angle .theta..sub.2 which is greater than .theta..sub.1. As a result, when it is desired to eject a disc an undesirably high pressure must be applied to the eject button 111. This of course deteriorates the operational characteristics undesirably.